1. Field of the Invention
The present invention relates to a device which is attached at the waist of a human torso, and which senses improper bending and sounds an audible alarm. More particularly, in industrial and other settings, when a person bends to lift a weight or perform some other activity, it is recommended for medical purposes that the person bend his or her knees and attempt to keep his or her spine upright. Most experts agree that improper bending occurs when a person bends at the waist to lift weight or performs some other activity. During bending, it is recommended that the bend at the waist does not exceed a predetermined lumbosacral angle. When a person bends the spine past this angle, most experts consider this improper bending that should be discouraged.
Devices that sense and respond to bending of the human body are disclosed in U.S. Pat. No. 4,938,476 to Brunelle et al., U.S. Pat. No. 4,665,388 to Ivie et al. and U.S. Pat. No. 4,958,145 to Morris. The Brunelle et al. patent discloses a device including a circuit having a mercury switch and an alarm for determining when the body bends beyond a predetermined lumbosacral angle. The Ivie et al. patent discloses a similar device. However, these devices have several drawbacks. Firstly, when an indicator is used in industry by a large number of people, it is often difficult to assure proper use of the device when it is meant for single side placement as shown in FIGS. 1 and 3 of the Brunelle patent. In practice, some people may find it more comfortable to wear the device on the right side, or it may be simply difficult to assure proper use because a person may switch the device to the non-sensing side. In addition, these prior art devices require a specific and complicated mechanism for attaching the back-angle-sensing devices.
These patents disclose the use of a buzzer to indicate to the person wearing the device that he has bent improperly. However, in industry settings, it is important for management to monitor how well a particular person follows recommended lifting technique over an extended period of time.
In addition, these patents disclose use of mercury switches that will sound an alarm each time the switch closes even in response to a simple jarring motion. For example, if a person moves abruptly, the mercury switch, or such other switch for sensing attitude, may connect the circuit and set off the buzzer. In almost any setting, it is annoying to have the buzzer sound when improper bending is not likely to occur or has not occurred.
It is, therefore, an object of the invention to provide a torso attitude sensor that can be worn on the left or the right side of a human torso and indicate improper bending regardless of which side the sensor is attached to. It is a further object of the invention to provide a device which will monitor personnel bending activity over an extended length of time, so that the person or management in a factory setting can determine whether or not recommended lifting techniques are being followed. It is a further object of the invention to prevent or minimize the number of false alarms in a back-bending sensing device.